The Localization of / 3 - Glucuronidase in the Early Chick Embryo

I N vertebrate tissues there appears to be a connexion between /3-glucuronidase and the proliferation of cells. This connexion was first noticed by Levvy, Kerr, & Campbell (1948) when they were investigating the effect of toxic compounds on mouse-liver glucuronidase. The early stages of embryonic development are characterized by rapid proliferations of cells and it is, therefore, of some interest to study the localization of /3-glucuronidase during these stages. Small amounts of /S-glucuronidase can be detected in the early embryos of Xenopus laevis (Billett, 1956) and in those of Drosophila melanogaster (Billett & Counce, unpublished). In these embryos no marked increase in the enzyme can be associated with the proliferation of cells. The large amount of yolk in the Xenopus and Drosophila embryos was a complicating factor in the above experiments. It was not possible to localize the enzyme in these embryos with a histochemical method. An embedding technique suited to the nature of the embryos and the requirements of the histochemical test could not be devised. It has, however, proved relatively simple to apply a modification of the Friedenwald & Becker (1948) technique to whole chick embryos cultivated in vitro. This technique, because of the diffuse nature of the reaction and the destruction of cytological detail which it entails, can only demonstrate the presence of /?-glucuronidase in particular cells or groups of cells (Billett & McGee-Russell, 1956). Intracellular localization of the enzyme is impossible. The method appears to be well suited to the present purpose, aimed at a histological rather than a cytological localization of the enzyme in the early chick embryo.